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Public Health Interventions Involving Travelers with Tuberculosis — U.S. Ports of Entry, 2007–2012

Every day, approximately 950,000 international travelers arrive in the United States (1). The Secretary of the U.S. Department of Health and Human Services is authorized to prevent the introduction, transmission, and spread of communicable diseases by travelers into and within the United States (2). The Secretary, through the CDC director, delegates this authority to CDC's Division of Global Migration and Quarantine (DGMQ). Of the communicable diseases for which federal quarantine and isolation are authorized by executive orders of the president (2), infectious tuberculosis (TB) is encountered most commonly by DGMQ's network of quarantine stations at major U.S. ports of entry (Table). Although legal immigrants and refugees undergo U.S. State Department–mandated TB screening overseas, CDC receives approximately 125 reports each year of arriving travelers with active TB, including foreign visitors, foreign students, and temporary workers (CDC, unpublished data, 2012). This report describes two cases that illustrate the TB control and prevention activities of quarantine stations. Such activities, including issuing federal isolation orders, restricting travel, arranging safe transport for patients across state lines, and conducting airline contact investigations, support CDC's mission to limit the spread of infectious disease from travelers.

Case Reports

Case 1. On March 24, 2010, the Nevada State TB Program notified the CDC Los Angeles Quarantine Station about an elderly legal immigrant from Mexico with infectious TB. The patient was admitted to a Nevada hospital in October 2009. Sputum smears revealed the presence of acid-fast bacilli (AFB), and standard four-drug treatment (isoniazid, rifampin, pyrazinamide, and ethambutol) was started empirically. The local TB clinic provided outpatient treatment under directly observed therapy until December 2009, when the patient abruptly left the United States for Mexico without notifying the clinic, and before drug susceptibility tests showed isoniazid resistance. Local public health officials referred the case to Cure-TB,* a binational TB program that facilitates continuity of care for patients with TB who travel between the United States and Mexico.

The patient returned briefly to the United States in March 2010, but made no contact with local TB control officers and departed again to Mexico. After discussions with state and local public health partners, CDC issued a federal isolation order and placed the patient on public health travel restriction lists (Do Not Board [DNB] and lookout lists) because of the risk for infectiousness resulting from suboptimal treatment, continued nonadherence with public health recommendations, and recent history of international travel. Persons included on the DNB list are assigned a public health lookout record, which alerts Customs and Border Protection (CBP) officers if the person attempts to enter the United States through any port of entry (3).

In September 2010, the patient was detected by CBP at a border crossing in El Paso, Texas. The CDC El Paso Quarantine Station served a federal isolation order, and the patient was transported to a nearby Texas hospital under CBP custody for evaluation and treatment. After three sputum specimens tested AFB smear-negative, the patient was escorted by a CDC quarantine public health officer to Nevada. The federal isolation order was rescinded, and the patient was transferred to the custody of a local health department for court-ordered home isolation. Compliance with an effective treatment regimen, administered through directly observed therapy, permitted removal of federal travel restrictions in November 2010.

Case 2. On October 18, 2011, the Ohio Department of Health TB Program reported a college student from China with AFB smear-positive, cavitary TB disease to the CDC Detroit Quarantine Station. In August 2011, the student had traveled from Japan to California on a commercial flight that exceeded 8 hours, and then flew on two connecting domestic flights (California to Illinois and Illinois to Ohio, each of which was <8 hours).

When DGMQ protocol conditions for TB airline contact investigations are met, including infectiousness criteria and flight duration of ≥8 hours, the jurisdictional quarantine station obtains the flight manifest and locator information for potentially exposed passengers on the flight (4). State health departments then are notified of contacts in their jurisdictions via the Epidemic Information Exchange (Epi-X), CDC's secure electronic communications network for public health professionals.

The CDC Detroit Quarantine Station obtained the international flight manifest and identified 15 passengers as contacts based on their seat assignments (passengers in the same row, two rows in front of, and two rows behind the index case). DGMQ notified nine state health departments of 11 U.S. resident passenger-contacts and the ministries of health of two countries about four passenger-contacts who lived outside the United States. Outcomes were reported to DGMQ by U.S. health departments for five passenger-contacts. Of those, two were evaluated and determined not to have been infected with TB; attempts to notify the other three were unsuccessful.

Editorial Note

In 2011, 10,521 new TB cases were reported in the United States, with rates 12 times higher in foreign-born persons than in U.S.-born persons (5). From June 2007 to December 2011, 632 cases of active TB among travelers were reported to CDC quarantine stations (CDC, unpublished data, 2012). TB transmission during air travel has been documented (4,6), but the risk for transmission has not been determined and is believed to be low. One model estimates the risk for transmission from a highly infectious passenger on an 8.7-hour commercial flight as 1 per 1,000 for all passengers, with higher risk to those seated closer to the infectious passenger (7). Delegated authority permits DGMQ's use of public health travel restriction tools and federal isolation orders to prevent persons known or suspected of having infectious TB from traveling. These tools can facilitate the safe transport of travelers with TB to local hospitals or their home states for testing and continued treatment. Since June 2007, five federal isolation orders have been served to persons with TB (inclusive of case 1), four of whom were foreign-born; before 2007, the last federal isolation order was issued in 1963.

Domestic or international public health officials may request that a person be placed on the DNB and lookout lists, which have been managed jointly by CDC and the Department of Homeland Security since formalization of the process in June 2007 (3). If persons on the lists are identified at ports of entry, CBP notifies the jurisdictional quarantine station to facilitate public health clearance or action. From June 2007 to December 2011, 205 persons with known or suspected TB were added to the DNB and lookout lists; 173 (84%) have since been removed after meeting criteria indicating noninfectiousness (CDC, unpublished data, 2012). The first case report, involving multiple health jurisdictions and CDC quarantine stations, exemplifies the successful use of the lookout record to intercept a TB-infected traveler at a land border and return the patient to public health management. The federal isolation order had been drafted months before the patient was encountered at the port of entry, facilitating immediate medical evaluation and return of the patient to health care in his home state.

The second case report highlights CDC quarantine stations' response to notifications of travelers with infectious TB who traveled by commercial aircraft. From June 2007 to December 2011, CDC quarantine stations, in collaboration with U.S. health departments, performed airline contact investigations for 390 travelers with infectious TB, involving 508 flights with approximately 15,650 potentially exposed contacts. DGMQ also notified foreign public health authorities in more than 50 countries of at least 3,000 international contacts (CDC, unpublished data, 2012). However, because outcome reporting to CDC is voluntary, contact tracing outcome reports typically are received for <20% of passenger contacts (4). In 2011, DGMQ used the results of epidemiologic and economic impact evaluations to revise its criteria for conducting airline contact investigations (Box). The policy changes conserve state and federal public health resources by assigning priority for tracing to the passenger-contacts of travelers who are most likely to transmit Mycobacterium tuberculosis (those with both positive sputum AFB smears and cavitation identified on chest radiograph)or who have multidrug-resistant TB. CDC quarantine stations also provide guidance to crews on ships regarding TB contact investigations when notified of travelers with infectious TB on maritime vessels.

In addition to responding to reports of infectious TB in travelers, four CDC quarantine stations meet immigrants arriving at U.S. ports of entry who have been diagnosed with admissible, noninfectious TB conditions during their pre-immigration medical screening, and provide them with a TB clinic referral in the states of their destination. Immigrants receiving referrals are four times more likely to initiate follow-up evaluation than those receiving no referral (p<0.001; CDC, unpublished data, 2012). Immigrants typically are not charged for these medical evaluations; the costs usually are borne by state and local health departments. Follow-up is important because newly arrived U.S. immigrants with a history of TB infection or previously treated disease have an increased risk for disease activation or reactivation during their first few years after arrival (8). DGMQ is developing a system to expand the referral program to include more CDC quarantine stations.

The network of CDC quarantine stations provides national leadership and coordination of public health responses to TB in travelers. DGMQ also communicates with foreign health authorities about TB patients or contacts who are no longer in the United States, and collaborates with U.S. health departments to work with TB patients who have left the United States but could return. Effective collaboration between CDC quarantine stations and international, state, and local public health practitioners can help reduce the spread of TB during travel by intercepting TB patients at ports of entry, returning patients to treatment, and identifying contacts for possible intervention.

The global burden of tuberculosis (TB) and the tremendous volume of travelers to the United States increase the risk for TB importation and transmission during travel. Significant resources are expended during public health responses to travelers with TB disease, including passenger contact investigations, legal measures, and implementation of federal travel restriction tools.

What is added by this report?

The case studies in this report illustrate the use of federal legal measures and travel restriction tools to help return noncompliant TB-infected persons to public health care, and highlight revised guidelines to optimize the cost-benefit ratio of airline TB contact investigations.

What are the implications for public health practice?

TB control in travelers into and within the United States can be promoted through ongoing state and local public health practitioner partnerships with their jurisdictional CDC quarantine stations and referral of immigrants with noninfectious TB conditions at ports of entry to TB clinics in their destination states.

TABLE. CDC quarantine stations and the jurisdictions in which they monitor ports of entry, 2012*

Index case was diagnosed within 3 months of the flight AND the flight occurred within 3 months of notification to the Division of Global Migration and Quarantine.

Flight lasted ≥8 hours gate-to-gate.*

Diagnosis of the index case was confirmed by sputum culture or nucleic acid amplification test for Mycobacterium tuberculosis AND is:

Sputum smear-positive for acid-fast bacilli AND cavitation is present on a chest radiograph; OR

Confirmed to have a multidrug-resistant isolate (regardless of the smear or chest radiograph results).

Note: A contact investigation will be considered on a case-by-case basis for situations that are unusual or not clearly addressed by the criteria. Examples include, but are not limited to, situations in which an unusually high proportion of close contacts have positive tuberculin skin test or interferon-gamma release assay test screening results, an index case has laryngeal tuberculosis, or cavitation is detected on chest computed tomography scan but no chest radiograph was performed.

* Gate-to-gate means all time spent on the aircraft, including boarding and deplaning time or delays on the tarmac.

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